Data from: Selective logging in tropical forests decreases the robustness of liana-tree interaction networks to the loss of host tree species

Selective logging is one of the major drivers of tropical forest degradation, causing important shifts in species composition. Whether such changes modify interactions between species and the networks in which they are embedded remain fundamental questions to assess the ‘health’ and ecosystem functionality of logged forests. We focus on interactions between lianas and their tree hosts within primary and selectively logged forests in the biodiversity hotspot of Malaysian Borneo. We found that lianas were more abundant, had higher species richness and different species compositions in logged than in primary forests. Logged forests showed heavier liana loads disparately affecting slow-growth tree species, which could exacerbate the loss of timber value and carbon storage already associated to logging. Moreover, simulation scenarios of host tree local species loss indicated that logging might decrease the robustness of liana-tree interaction networks if heavily infested trees (i.e. the most connected ones) are more likely to disappear. This effect is partially mitigated in the short term by the colonization of host trees by a greater diversity of liana species within logged forests, yet this might not compensate for the loss of preferred tree hosts in the long term. As a consequence, species interaction networks may show a lagged response to disturbance, which may trigger sudden collapses in species richness and ecosystem function in response to additional disturbances, representing a new type of “extinction debt”.

选择性采伐（selective logging）是热带森林退化的主要驱动因素之一，会造成物种组成发生显著改变。此类变化是否会改变物种间的相互作用及其所嵌入的相互作用网络，仍是评估采伐后森林“健康”状态与生态系统功能的核心议题。本研究聚焦马来西亚婆罗洲这一生物多样性热点地区（biodiversity hotspot）内，原生林与选择性采伐林中藤本植物（lianas）与其寄主树木（tree hosts）之间的相互作用。研究发现，相较于原生林，采伐林中的藤本植物丰度更高、物种丰富度更大，且物种组成存在显著差异。采伐林中的藤本负荷更高，且会差异化影响慢生树种，这可能加剧采伐本身已造成的木材价值损失与碳储量下降。此外，针对寄主树木局域物种丧失的模拟情景研究显示，若重度侵染树木（即连接度最高的个体）更易消失，则选择性采伐可能降低藤本-树木相互作用网络的鲁棒性（robustness）。短期内，采伐林中更多样化的藤本物种定植寄主树木可部分缓解这一效应，但从长期来看，这或许无法弥补偏好寄主树木的丧失。因此，物种相互作用网络可能对干扰表现出滞后响应，在遭遇额外干扰时可能引发物种丰富度与生态系统功能的突发性崩溃，这属于一种新型的“灭绝债务（extinction debt）”。